Filed Sept. 28, Sheets-Sheet INVENTOR, Z624262sseaze ?????. ATTORNIEKS.

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1 Filed Sept. 28, Sheets-Sheet BY INVENTOR, Z624262sseaze?????. ATTORNIEKS.

2 June 19, 1956 L. B. ROSSEAU 2,751,311 ALUMINIZING Filed Sept. 28, Sheets-Sheet 2 N INVENTOR. Z?e?? B ATTORNEYS.

3 June 19, 1956 L. B. ROSSEAU 2,751,311 ALUMINIZING Filed Sept. 28, Sheets-Sheet 3 Lp- ' ' NNNNNNNNNNNNNNNNNNNNNNNN? LiiSiii SiiiLiLSSiSiSiSi SiSiSiS ilisiis SiS iiililisiis iissi isiiilssisqs? NNNNNNNNNNN. N. N.N. (k???????????????? ATTORNEYS.

4 June 19, 1956 L. B. ROSSEAU 2,751,311. ALUMINIZING Filed Sept. 28, Sheets-Sheet INWENTOR.?????????????????? ATTORNEYS.

5 United States Patent Office 2,751,311 Patented June 19, ,751,311 ALUMNEZING Leon B. Rosseau, Penn Valley, Narberth, Pa., assignor to Ajax tion of Electric Pennsylvania Company, Philadelphia, Pa., a corpora Application September 28, 1954, Serial No. 458,821 4 Claims. (Cl ) The present invention relates to methods of selective 5 aluminizing or otherwise coating steel or the like and selective aluminizing or other coating furnaces. Very effective aluminizing processes have been de veloped which coat aluminum on ferrous metals by first cleaning the ferrous metals such as steel in a flux which is 20 rectified by maintaining it in contact with a pool of molten aluminum and then dipping the articles in molten alu Ininum. See Grange and Hanink, U. S. Patents 2,544,670 and 2, 544,671, Grange U. S. Patent 2,569,097 and article by Hanink and Boegehold, SAE Annual Meeting, Detroit, 25 Mich., March 12, It has been difficult in carrying out the process of aluminizing to control the depth of aluminum application to the articles being coated so as to permit selective alu minizing of part only of the article, while retaining other 30 parts of the article free from aluminum coating. The present invention is directed particularly to the technique of selective aluminizing and the apparatus by which aluminum can be coated only on certain prede ing termined from parts other of parts. the article, omitting the aluminum coat 35 The problem of selective aluminizing involves some difficulties, because the flux is most suitably heated by a submerged electrode furnace of the Hultgren type, and contact of the molten aluminum with the electrodes is to 40 be avoided as it would cause a short circuit, but on the other hand it is necessary to maintain constant contact between the flux and the pool of molten aluminum in order to rectify and purify the flux, while the articles which are being coated should be submerged not only 45 beneath molten aluminum but beneath flux on the molten aluminum. It should be understood that the practice has been to heat the flux in a submerged electrode furnace having a shallow pool of molten aluminum at the bottom, the molten aluminum in the pool being below the elec 50 trodes and being heated by heat conductivity from the flux. The aluminum is heavier than the flux commonly used and suggested by the literature, such as the patents and article referred to. Usually the molten aluminum at the bottom of the furnace chamber has a depth between 55 a few inches and for example 18 inches. The present invention is concerned with applying molten aluminum to restricted or limited areas only of the article being coated, and accomplishing this result in the same furnace in which the articles are desirably preheated, keeping the articles beneath the surface of the flux until after the completion of coating and detearing. The cost of the equipment is thus kept at a minimum while retain ing flexibility in the operation. Excellent results are secured not only in respect to adherence over the limited areas coated, but also in regard to rapid removal of excess aluminum from the coated area and securing uniformity of coating thickness, since the fluxing salt is present im mediately as the article emerges from the aluminum, and the inertia or shock and washing effect by the salt when the article coated is withdrawn further assists in removing aluminum. excess aluminum, which is received in the body of molten An example of the character of work which may be coated selectively is the seating portion of automotive from intake coating. and exhaust valves, while keeping the stem free A purpose of the invention is to obtain uniform and adherent aluminum or other metal coatings on selective areas of steel and other ferrous alloys. A further purpose is to coat selective areas to an ac aluminum curate level bath. while maintaining a flux coating on the A further purpose is to maintain the surfaces of the ferrous metal articles to be aluminized beneath the flux while dipping the articles to a predetermined level below the top of the articles, and subsequently removing excess aluminum while flux contact is maintained as the coated portion of the article is removed from the aluminum bath. A further purpose is to aid the detearing of a ferrous metal article aluminized over a selected area by shock applied at the time of removal. claims. Further purposes appear in the specification and in the In the drawings I have chosen to illustrate one only of the numerous embodiments in which my invention may appear, selecting the forms shown from the standpoints of convenience in illustration, satisfactory operation and clear demonstration of the principles involved. Figure 1 is a fragmentary diagrammatic top plan view of an aluminizing furnace according to the invention, eliminating the work holding fixtures and the work. Figure 2 is a fragmentary diagrammatic vertical section on the line 2-2 of Figure 1. Figure 3 is a fragmentary diagrammatic vertical trans verse section on the line 3-3 of Figure 1. the Figure line is in an Figure end elevation 1. looking in the direction of Figure 5 is a fragmentary sectional perspective show ing a suitable pusher bar arrangement. work Figure holding 6 is a fixture. diagrammatic side elevation of a suitable Considering now the drawings in detail, the furnace of the present invention comprises a body 20 having frame 21, an insulating layer 22 held by the frame, and a refractory lining 23 inside the insulating lining which forms a furnace chamber 24 suitably open at the top. The furnace chamber contains a pool of molten alu minum 25 at the bottom and a body of molten flux 26 adjacent above the the molten top of aluminum the furnace. and extending to a point Metallic electrodes 27 of the submerged salt bath heating type common in the Hultgren furnace, suitably extend over the top and into the furnace chamber to a depth above the pool of molten aluminum 25. The electrodes are suitably mounted and insulated at 28 and connected to transformer means 30 suitably supplied with alternating current at commercial voltage and frequency. ipyrometric control 35 is provided to control the heat and maintain the desired temperature. Suitable stirring means 32 is employed to agitate the molten flux. Any suitable mechanism may be used to support and advance the articles to be aluminized in position beneath the level of the flux. I illustrate work supporting trays 33 having suitable supporting arms 34 which mount work pieces 35 at the desired level and in the desired position for aluminizing. The detail of the clamps or clips to hold the work is not shown. The workpieces here shown are automotive valves with the seating portions located at the bottom for immersion and all at the same level. The stems extend upward. The work supports desirably are suspended from headers 36 having bar engaging portions 37 which ride or

6 2,751, is provided with a hook 72 that engages the bar 36 and slide on rails 38 which extend on either side longitudinal raises the work at a velocity not less than 10 feet per ly of the furnace and above the level of the electrodes. minute, and preferably greater. The jolt as the hook The mechanism for advancing the work support here engages is desirably abrupt. This has the effect of re is shown as pusher bars 40 having dogs 41 pivoted there moving adiditional molten aluminum by inertia effect on intermediate their ends at 42 and extending up at 43 and by the washing of the coated article in the molten above the rails in normal operating position. The dogs flux as it is withdrawn. are overbalanced to restore to the position of Figure 5. The coated article is then suitably processed, a desir The pusher bars suitably have rollers 44 which ride the able sequence being cooling in an air blast for two sec bottom of the rails on a suitable box section and the dogs 0 onds, air cooling to 800 F. or less in three to four extend up through a slot 45 at the top of the box section. The pusher bars are reciprocated back and forth by minutes, washing in water to remove excess flux for 45 seconds, followed by a brightening dip, a hot rinse and fluid actuated cylinders 46 which move piston rods 47 pivotally connected at 48 to the pusher bars. As the an oil dip for corrosion protection of uncoated surfaces. pusher bars advance, the dogs move the work supports The depth of immersion in the aluminum is conveni ently controlled where selective dipping is being per forward and as they retract, the dogs tilt under the next formed by any suitable means, desirably using hand rearward work support until the dogs move behind it, wheel 73 turning in bearing 74 carrying screw 75 which and then the dogs rise to engage and advance it. The work supports first bring the work beneath the engages nut portion 76 on the bottom of slide 77 which flux at position 50, thus preheating the work to a suitable is guided on guide 78 and carries the entire cam, cam 20 temperature. If only a certain portion is to be dipped, support and piston assembly forward to compensate for the preheating and fluxing may be limited only to this exhaustion of molten aluminum in the bath 57. The portion. In a typical example, a temperature of 1325 hand wheel is suitably turned when inspection of the F. and a time of five minutes is used for preheating work indicates it should be dipped deeper. When it is small parts beneath the flux. desired to replenish the molten aluminum, aluminum is 25 The parts advance under pusher bar action through poured into the container 57 suitably to fill it, any excess positions 51, 52, 53, 54 and finally positions 55 at the entering the pool 25 at the bottom of the furnace. The right in Figure 2. Beneath position 55 is located a con adjustment at wheel 73 is then reset to zero and the oper tainer 56 containing a pool of molten aluminum 57. The ation continued allowing for further exhaustion. container is normally entirely below the flux and sup In view of my invention and disclosure variations and 30 ported by a frame 58 from hanger arms 60 pivoted at modifications to meet individual whim or particular need 61 on a yoke 62 which at the other end is pivoted at will doubtless become evident to others skilled in the 63 on a cross shaft 64 secured to the furnace frame. The art, to obtain all or part of the benefits of my invention yoke has a follower roller 65 on a lower surface inter without copying the method and structure shown, and I, mediate its ends and the follower roller rides cam 66 therefore, claim all such insofar as they fall within the 35 which reciprocates on guiding rollers 67 on a support reasonable spirit and scope of my claims. 68. The cam is manipulated by a piston and rod com Having thus described my invention what I claim as new bination 70 actuated by fluid cylinder 71. In operation, the first work support is lowered to posi tion 50 by any suitable hoisting mechanism and is ad vanced to position 55 by repeated reciprocations of the pusher bars. In position 55 the work is poised above the molten aluminum bath 57 in the container 56. By for ward motion of the cam 66 the yoke is raised and the container is raised until the molten aluminum, still below the level of the flux, dips the work to the predetermined level. In the case of the inlet and exhaust valves, this is preferably just enough to cover the seating portions. The temperature and time of immersion will be suitably regulated. In a particular example, the molten aluminum is maintained at 1300 to 1325 F. and the immersion time is preferably 5 to 10 seconds for the valves men tioned. After the immersion is completed, the cam 66 is re tracted and the molten aluminium drops below the level of the work, and the work immediately comes in contact with the flux. This is very desirable as it promotes de tearing, since the flux tends to make the molten aluminum flow more readily. The drip time may suitably be 15 seconds in a particular example, the flux being at 1325 F. Any drip is caught in the container 56. It should be emphasized that the molten aluminum leaves contact with the work and the flux regains contact with the work without any air contact and the dripping continues without air contact, thus avoiding oxidation and interference with the coating adherence. The work is now preferably subjected to shock (in cluding vibration) as it is withdrawn. This is desirably accomplished by an automatic hoisting mechanism which and desire to secure by Letters Patent is: 1. The method of selectively aluminizing, which com prises maintaining a bath of molten flux, maintaining a body of molten aluminum beneath the flux and in 60 contact therewith to rectify the flux, immersing metal articles to be aluminized beneath the flux, maintaining a second body of molten aluminum beneath the fux, rela tively raising the second body of molten aluminum until it surrounds at least a portion of the metallic articles to 65 be aluminized while maintaining the second body of molten aluminum at all times beneath the level of the flux and then relatively lowering the second body of molten aluminum with respect to the metallic articles being coated and reestablishing instantaneous contact of flux with the articles which have been coated. 2. The method according to claim 1, in which only the lower portions of the articles are immersed beneath the second body of molten aluminum. 3. The method according to claim 1, in which the articles are rapidly moved upward out of the flux to wash off excess aluminum by the flux. 4. The method according to claim 1, in which the articles are moved out of the flux and are concurrently subjected to shock. References Cited in the file of this patent UNITED STATES PATENTS 2,293,747 Koch Aug. 25, ,477,684 Borg et al Aug. 2, ,515,488 Boller et al July 18, 1950